Kevin Joseph Edgar

Advances in cellulose ester performance and application

Abstract In this review, we examine those areas of cellulose ester application in which there has been the greatest recent activity, and we choose to define the word ‘recent’ to include roughly the last 20xa0years. We focus on work that increases understanding of cellulose ester structure-property relationships, as well as how they relate to performance in specific applications. Our focus is on the performance of cellulose esters in modern coatings, controlled release of actives, plastics (with particular focus on biodegradable plastics), composites and laminates, optical films, and membranes and related separation media. We think that the review will prove useful to those who work with cellulose esters in these and related applications, as well as those who may wish to use this background to help them imagine new ones.

Pharmacokinetics of letrozole in male and female rats: influence of complexation with hydroxybutenyl-β-cyclodextrin

Cyclodextrins (CDs) are one of the most successful solutions to the problem of poor drug solubility. In this study, we examined the in‐vitro effects of three CDs on the solubility of letrozole, a breast cancer drug that is practically insoluble in water. The most promising, hydroxybutenyl‐β‐cyclodextrin (HBenβCD), was used for in‐vivo studies in male and female Sprague‐Dawley rats. Letrozole is a drug with dramatic gender‐based differences in pharmacokinetics. For example, the terminal half‐life (t1/2) of letrozole following intravenous administration in male rats was 11.5 ± 1.8 h (n = 3), while in female rats it was 42.3 ± 2.9 h (n = 3). HBenβCD increased the solubility and enhanced the dissolution rate of letrozole. Complexation of letrozole with HBenβCD improved oral absorption in male rats and maximized absorption in female rats. Regardless of gender, the presence of HBenβCD in the formulation increased the in‐vivo rate of absorption. When administered in a capsule formulation with letrozole, HBenβCD resulted in a higher Cmax (61% in male rats, 42% in female), shorter Tmax values (8.4 to 6.3 h in male, 16.4 h to 5.4 h in female) and increased absolute oral bioavailability (46 ± 2 vs 38 ± 3 in male, 101 ± 3 vs 95 ± 2 in female). Thus, solubility limits both rate and extent of letrozole absorption in male rats, but limits only the rate of absorption in female rats.